Which components are included in Multiple Endocrine Neoplasia type 2a (MEN2a)?

• A. Pheochromocytoma and diabetes
• B. Medullary thyroid carcinoma and adrenal carcinoma
• C. Medullary thyroid carcinoma and parathyroid hyperplasia
• D. Pancreatic adenoma and hyperparathyroidism

Answer: (C)

Multiple Endocrine Neoplasia type 2a (MEN2a), also known as Sipple syndrome, is characterized by a specific set of endocrine tumors. The hallmark components of MEN2a include medullary thyroid carcinoma, primary hyperparathyroidism, and pheochromocytoma.

Medullary thyroid carcinoma is a significant feature of this syndrome, originating from the parafollicular C cells of the thyroid, which secrete calcitonin. The presence of parathyroid hyperplasia leads to hypersecretion of parathyroid hormone (PTH), resulting in hypercalcemia. Although pheochromocytoma is also a part of MEN2a, it was specifically noted that the correct option details the presence of both medullary thyroid carcinoma and parathyroid hyperplasia.

This combination is distinct for MEN2a and helps in diagnosing the syndrome as part of the genetic predisposition associated with mutations in the RET proto-oncogene. Thus, the components mentioned align perfectly with the known clinical manifestations of MEN2a.